A liquid crystal compound can form a liquid crystal layer, which behaves as both liquid having fluidity and crystal consisting of regularly aligned molecules under some conditions. The liquid crystal compound is widely used in various liquid crystal devises such as a liquid crystal display. In producing any devises, it is important to control alignment (orientation) of the liquid crystal molecules. Examples of the alignment include homeotropic alignment, homogeneous alignment, tilt alignment, hybrid alignment, twisted alignment, planar alignment and focal conic alignment. The alignments are described in “Basics and Application of Liquid Crystal (written in Japanese)”, Kogyo Chosakai Publishing Inc., 1991.
Alignment of a liquid crystal compound generally depends on alignment technique and a character of the liquid crystal compound. The alignment technique can be applied to a surface of substrate in a conventional manner described in “Basics and Application of Liquid Crystal (written in Japanese)”, Kogyo Chosakai Publishing Inc., 1991). Various alignment techniques have been proposed. For example, Appl. Phys. Lett., 27(1975), pp. 268; ibid., 29(1976), pp. 67; and ibid., 22(1973), pp. 111 disclose a process for chemically adsorbing an aligning promoter such as chromium carboxylate complex or organosilane on a surface of substrate to align the liquid crystal molecules vertically or horizontally. Ouyo-Butsuri (written in Japanese), 43(1974), pp. 18; Phys. Rev. Lett., 25(1976), pp. 67 discloses a process of adsorbing an aligning promoter physically on a substrate surface to align the liquid crystal molecules vertically or horizontally. Appl. Phys. Lett., 24(1974), pp. 297 discloses a process of polymerizing and adsorbing a substance of low molecular weight on a substrate surface by plasma discharge to align the liquid crystal molecules vertically or horizontally. J. Appl. Phys., 47(1976), pp. 1,270 discloses a process of polymerizing and adsorbing a substance of high molecular weight on a substrate surface by an electric field of high voltage to align the liquid crystal molecules vertically or horizontally. Appl. Phys. Lett., 25(1974), pp. 479 discloses an oblique deposition method to cause oblique and homogeneous alignment. In the oblique deposition method, oxide such as silicon oxide is obliquely deposited on a substrate. A vertically aligning promoter can be used in the oblique deposition method to align molecules vertically and obliquely. Summaries of 6th Forum on Liquid Crystal (in Japanese), (1980), pp. 96 discloses a process of depositing an oxide such as silicon oxide obliquely while rotating a substrate to cause vertical and oblique alignment.
As described above, various aligning techniques have been proposed. Further, a process of obliquely aligning liquid crystal molecules has been proposed. However, it is difficult to control a tilt angle sufficiently according to the techniques. Accordingly, an agent capable of controlling the tilt angle has been desired. The agent should have a function of controlling the tilt angle in alignment of liquid crystal molecules easily.
Each of International Publication Nos. 98/40375, 97/33882 and U.S. Pat. No. 4,978,659 discloses a 1-azabicyclo[3.2.0]heptane derivative having dimethylamino-pyridinium group at a terminal of side chain. The 1-azabicyclo[3.2.0]heptane derivative is proposed for medical or pharmaceutical use.
Each of Japanese Patent Provisional Publication Nos. 2002-37776, 2002-37777, 2002-38158, 2002-62533 and 2002-62531 discloses an aminopyridinium derivative substituted with an aliphatic group. The publications also disclose a method of using the derivative to control a tilt angle in alignment of liquid crystal molecules.